How to order windows of the same program on taskbar

I'm using Windows 8 and appreciate the ability to reorder my programs at will in the taskbar. However, for different windows of the same program - I have three Firefox windows, for instance - I can't seem to reorder them; what's worse, they seem to regularly switch themselves around for no reason I can see.

I usually want my main Firefox window to be the first (leftmost) one in the taskbar, with my work window second and the third window last, but every now and then they get mixed up and I have to get used to remembering which is which all over again, and I can't figure out how to manually fix them. I think this happens with programs other than Firefox too, but I suppose I could be misremembering.

1. 
   

   Is there any way to reorder the taskbar buttons corresponding to multiple windows of the same program manually?

   
   


2. 
   

   Why does the order of my Firefox windows keep shifting around? Is there a way to ensure it keeps the order straight?

   
   

Answer

Figured I'd share how I got this solved.

Scott's comment pointed me to this question: Reorder Windows 7 taskbar items The accepted answer to that points to a program now called 7+ Taskbar Tweaker, which as it turns out works with Windows 8 as well as 7 now. It not only offers options for easily reordering windows within a taskbar group (either by right-clicking and dragging the taskbar tabs themselves or by dragging the preview windows), but also a whole lot of further options for customizations and conveniences. So for anyone else frustrated with this, that program is exactly what you're looking for and more.